Field
Implementations described herein generally relate to semiconductor manufacturing and more particularly to real-time temperature control of an electrostatic chuck and method of using the same.
Description of the Related Art
As the feature size of the device patterns get smaller, the critical dimension (CD) requirements of these features become a more important criterion for stable and repeatable device performance. Allowable CD variation across a substrate processed within a processing chamber is difficult to achieve due to chamber asymmetries such as chamber and substrate temperature, flow conductance, and RF fields.
In processes utilizing an electrostatic chuck, uniformity of temperature control across the surface of the substrate is even more challenging due to the non-homogeneous construction of the chuck below the substrate. For example, some regions of the electrostatic chuck have gas holes, while other regions have lift pin holes that are laterally offset from the gas holes. Still other regions have chucking electrodes, while other regions have heater electrodes that are laterally offset from the chucking electrodes. Since the structure of the electrostatic chuck can vary both laterally and azimuthally, uniformity of heat transfer between the chuck and substrate is complicated and very difficult to obtain, resulting in local hot and cold spots across the chuck surface, which consequently result in non-uniformity of processing results along the surface of the substrate.
The lateral and azimuthal uniformity of heat transfer between the chuck and substrate is further complicated by heat transfer schemes commonly utilized in conventional cooling plates to which the electrostatic chuck is mounted to form a substrate support assembly. For example, conventional cooling plates typically have only edge to center temperature control. Additionally, during production runtime, the temperature profile of the cooling plates may vary from substrate to substrate as substrates are moved into and out of the processing chamber. Thus, local hot and cold spots within the electrostatic chuck are difficult to control while utilizing the heat transfer features of conventional substrate supports over the production runtime.
Thus, there is a need for an improved substrate support assembly.